Although most stenoses do not occur at the ostium of an artery, there are thousands of cases each month where the mouth of an artery (the ostium) is substantially obstructed at its aortic take-off; this is called an aorto-ostial lesion. In such cases, the interventional cardiologist or radiologist is frequently unable to place the stent's proximal end within ±2 mm of the ostial plane. Two types of incorrect stent positions are (1) when the stent's proximal end extends more than 2 mm into the aorta, and (2) when the stent's proximal end is placed more than 1-2 mm into the artery distal to the ostial plane.
In U.S. Pat. No. 6,458,151, F. S. Saltiel describes an ostial stent positioning device. However, the most important feature of such a device; namely, and expandable distal portion that touches the wall of the aorta near the ostium of the artery to be stented is not optimized for easy usage of such a device. Furthermore, the Saltiel design is essentially a cylindrical sheath within the guiding catheter which sheath extends for the entire length of the guiding catheter. Such a design would have an incredible amount of friction between the cylindrical sheath and the interior wall of the guiding catheter that would make it very difficult to operate. In addition, the Saltiel design would substantially obstruct the internal cross-section of the guiding catheter along its entire length, limiting the injection of contrast material, and the passage of guide wires, balloon catheters, and/or stents.
In U.S. Pat. No. 5,749,890, A. Shaknovich utilizes a stent mounted on a catheter that has an inflatable section that touches the wall of the aorta in the vicinity of the ostium of the artery that is to be stented. Such a design precludes an accurate stent positioning system that can be used with the stent delivery system of any manufacturer.